1. Field of the Invention
This invention relates generally to devices for preventing damage to the chain ring, chain, crank and bottom bracket of a bicycle and devices that maintain the chain safely on the teeth of the chain ring. Specifically, the invention improves upon the prior art by uniquely integrating a chain guide with an improved chain ring protector.
2. Description of the Related Art
The forward portion of the bicycle drivetrain, consisting of the bottom bracket bearings, crank, chain ring, and chain is vulnerable to damage from underside impacts with rocks, stumps and other road and trail obstacles. The need to protect this part of the bicycle from such impacts, particularly during off-road cycling, has been addressed with round plates of metal or plastic that rotate with the chain ring and also with appliances that attach to the bicycle's lower frame tubes and act as a protective undercarriage.
An even more practical device is disclosed in U.S. Pat. No. 7,066,856, which is incorporated herein by reference, and which is assigned to the assignee of the current application. It consists of a bracket portion that mounts to the bottom bracket shell of the bicycle frame and a semi-circumferential guard portion that extends from the bracket to below the chain ring. The guard portion deflects trail obstacles that otherwise would damage the chain ring or other forward drivetrain components.
In addition to a device for protecting the chain ring from impacts, it is advantageous for the bicycle to be equipped with a device for maintaining the chain securely on the chain ring. The same rough terrain that presents underside obstacles capable of damaging the drivetrain can, when struck by the bicycle's wheels, jar the entire bicycle, thereby causing the chain to shake violently enough to derail it from the chain ring. A derailed chain can result in damage to mechanical components as well as inconvenience and even physical danger to the rider.
The need exists for a chain guide and chain ring protector. Other novel advantages of the combined device will become apparent in the following specification.